thats a really great bot.
i know you can stack high but what if when you are stacking and ur bot gets hit how will the boxes be kept from falling? Also, how high can you stack?

Travis Covington

02-17-2003, 06:46 PM

we grab the bottom box and the ones above it are only supported by the bottom one...sooo if we get hit hard they will most likely topple (except the one we have grabbed)

we can place any number of boxes at or below 6 boxes high

refer to the other picture...

this design might change in the next two days... we have learned at the scrrf sectional that stacking might not be the best thing to do (we had to lose our 4 motor 2 speed gearbox because we were overweight and are regreting that)

jburstein

02-18-2003, 04:58 PM

gee- i've seen that exact wheel setup before. Like on our robot last year, and on this year's robot too before we moved on to new and better things. Seriously the only difference between your drivetrain and ours (aside from the motors which i can't see, but i suspect your setup is similar to ours)is that we used a 60 tooth sprocket on our wheel, and you're using what looks like a 45 tooth or so.

I'm wondering how well you guys turn, because I know turning was out of the question for us...

Travis Covington

02-18-2003, 05:34 PM

they are 72 tooth sprockets on the wheels, 1/4 pitch

they are 8" x 2" bead-lok skyway wheels shaved down about 2 inches with added belting

the height of the modified wheel is about 7 inches with the belting

we turn fine, we used the same setup last year

the motors currently are just the 2 drill motors, we have a 4 motor 2 speed gearbox but are unable to use it because of weight (it weighs another 15 lbs over our already overweight robot)

Thorin

02-19-2003, 12:52 AM

ok and if the boxes arent stacked perfectly right side up? hehe

LoganB

02-19-2003, 01:20 AM

Can't wait to see how a bot like that will do in the competition

sanddrag

02-19-2003, 01:51 AM

At Chatsworth it didn't really have a chance to stack anything (nor did anyone else) and it got flipped easily.

Lindy

02-19-2003, 04:11 AM

Originally posted by sanddrag
At Chatsworth it didn't really have a chance to stack anything (nor did anyone else) and it got flipped easily.

Ouch. Well, in defense of our poor bot, I didn't see a lot of stacking from any other robots either -- it was mostly a box shoving match down there.

As for flipping... Embarrassingly, it did topple twice during competition. Of course, I heard that it was under certain circumstances and the guys are fixing up a solid panacea in the interim before shipping.

So the toppling will be resolved (some shifting of components to alter CG is part of the package), and I think the box grabbing mechanism is also to be changed. That's all I could say -- I'm a programmer and am clueless when it comes to mechanical design and engineering anyway. So I guess my talk is all moot. Wee!

Katy

02-19-2003, 04:20 AM

Wow...that's something. Is that thing top heavy at all? Those bars look thick.

Travis Covington

02-19-2003, 09:52 AM

As of 6:00 am this morning it is no longer top heavy. (never really was, but it definitely isnít now)

The bars are 30mm tube approximately 1/6th of an inch thick (welded and powder-coated)

The arms and grabbing mechanism is about 15 pounds total.

The chassis is very heavy weighing in at around 80 pounds it self (that puts the CG, when driving normally, currently at about 8 inches off the ground

If you really think about it, the only weight that is up high are the vertical supports and the tube frame (4-bar linkage). As we raise boxes of course it becomes top heavy, the boxes weigh 4.5 pounds a piece!! But we do not lift the boxes until we are directly in front of the stack we want to place the boxes on.

In regards to the question about the boxes not being perfectly stacked straight upright. We have a rotation device on the grabber that allows us to spin the box to the correct orientation.

And again in defense of our robot, as Lindy said, it tipped twice due to driver error.

The first time because we were trying to push the boxes over and jerked the joystick in reverse while being pushed by a robot and a stack of boxes...

The second time was even more so driver error where we simply jerked the joystick in the wrong direction causing the robot to tip and then fall.

Currently we are adding wheelie bars, which will completely prevent our robot from even coming close to tipping

In regards to the feasibility and practicality of stacking boxes... you have to remember that QP's are what get you into finals...
The higher the stack the higher the multiplier and the more points you get (win or loss).

You can argue and criticize but this is supposed to be fun, you guys don't need to argue to my team about a robot you know nothing about.

I am happy to answer questions but please donít jump to conclusions.

This is my 6th year with a FIRST robotics. 4 years in high school and 2 years now with my current team as a Mechanical Engineering student in college. I would like to think I know what I am talking about.